Your back-light inverter is most likely the cause, if you take apart the back it is the small board on the right .
Good luck finding one I have been looking for two months for one because I have the same condition. The only other thing is to take it to a repair shop, they seem to have the market cornered in the repair aspect.
If you do find one please post so I could also get one.
Roger R
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix televisions.